Dry mixes for use in electrolytic



Patented June 27, 1950 DRY MIXES FOR USE IN ELECTROLYTIC RECORDINGHarold G. Greig, Princeton, N. J., assignor to Radio Corporation ofAmerica, a corporation of Delaware No Drawing. Original applicationNovember 4, 1944, Serial N0. 562,032. Divided and this ap plicationSeptember 26, 1947, Serial No. 776,411

4 Claims. 1

The present invention relates to dry stable mixes for use in preparingsolutions for the electrolytic preparation of colored images on atraveling web or band which for simplicity may be referred to as areceiver. This application is a division of my co-pending applicationSerial No. 562,032, filed November 4, 1944, now Patent No. 2,442,596,granted June 1, 1948.

The production of color image records by electrolyzing a solutioncontaining a diazotizable amine, a nitrite, an electrolyte such assodium chloride, potassium chloride and the like and a coupler, isdisclosed in Solomon U. S. P. 2,306,471. In my co-pending applicationSerial No. 562,033, filed November 4, 1944, now Patent No. 2,493,963,granted Jan. 10, 1950, and entitled Electrolytic Recording, it issuggested that there be substituted for the amine and nitrite of suchsolution a stabilized diazo amino compound. Manifold advantages,including an improved stability of the records to light, are obtainedwhen operating in this way. It has been found that these two methods arethe most eiiicacious for electrolytically producing color image recordsespecially in facsimile recording. By the term facsimile recording asused herein is meant not only the reproduction on the receiver of apre-existing subject, but also the reception of subject-matter in theprocess of creation or formation.

The production from dry mixes of the electrolytic recording solutionswith which the receiver is treated in these methods has manifestadvantages. If the dry mix be storage stable, it can be prepared in bulkand stored for a considerable period of time. Furthermore, it can beshipped to whatever destination desired at a much lower cost than thewater solutions. The production of dry mixes suitable for use in theseprocesses has accordingly been a desideratum in this art.

The couplers which have been found to give best results in the methodspreviously outlined are naphthol sulfonic acids, of which chromotropicacid is an example. This acid is usually sold in the form of itsmono-sodium salt. This salt is acid and if incorporated into a dry mixcontaining a diazotizable amine and a nitrite or a stabilized diazoamino compound, it would induce premature diazotization and coupling inthe first instance, and premature splitting of the diazo amino compoundand coupling in the second 2 instance. If, on the other hand, thealkalinity of such compounds be increased to avoid such premature actionby the utilization of the usual alkalies such as sodium hydroxide,sodium car- 'lbonate, potassium hydroxide, and the like, it is foundthat the records obtained suffer because of a poor shade of the imagesand because of the instability of the background to light. It hastherefore been considered preferable, up to the present time, to preparefresh solutions for electrolytic recording rather than to produce drymixes which can be stored and shipped for use at a time in the futuredespite the advantages inherent in the latter course of action.

I have now discovered that the objections to in water in theconcentrations in which they are used in electrolytic recording to givea pH of approximately 9.5. The alkalinity induced by using thealkylolamine prevails during storage so that no premature diazotizationor splitting of the diazo amino compound with resulting coupling takesplace. Due to the stability of such compounds or to some other as yetunascertained property thereof, solutions in water or another suitablesolvent such as alcohol of dry mixes containing the same, produce onelectrolysis, dark image records the background of which has a muchhigher permanence to light than records" obtained where the alkalinityhas been produced by resort to the usual alkalies.

It is accordingly an object of my invention to produce dry mixes for theproduction of electrolytic recording solutions wherein the couplingcomponent is a naphthol sulfonic acid in which at least one sulfonicacid group has been neutralized with an alkylolamine.

It is a further object of my invention to produce dry mixes for theproduction of electrolytic" recording solutions wherein the couplingcompound is a naphthol polysulfonic acid in which at least one sulfonicacid group has been neutralized with an alkylolamine.

It is a further object of my invention to pro-,

duce storage stable dry mixes containing a pri mary aromatic amine, anitrite, an electrolyte and a naphthol sulfonic acid as the couplingcompound in which at least one sulfonic acid group has been neutralizedwith an alkylolamine.

It is a further object of my invention to produce storage stable drymixes of a stabilized diazo amino compound, an electrolyte and as thecoupling compound a naphthol sulfonic acid at least one of the sulfonicacid groups of which has been neutralized with an alkylolamine.

It is a further objectof my invention to produce records byelectrolyzing a solution containing a source of diazonium ions, anelectrolyte, and as a coupling compound a naphthol sulfonic acid inwhich a sulfonic acid group has been neutralized by an alkylolamine.

It is a further object of my invention to produce dry mixes for formingelectrolytic recording solutions in which the coupling compound ischromotropic acid, the sulfonic acid groups of which have beenneutralized by an alkylolamine.

Further objects of my invention will appear as the description proceeds.

It has been stated the dry mixes of the present invention contain eithera diazotizable amine and a nitrite or a stabilized diazo amino compound.In other words, the diazonium ions which react with the couplingcomponent are produced by the action of the facsimile recording currenton the diazotizable amine and the nitrite on the one hand and the diazoamino compound on the other hand. The diazotizable amine or the arylamine from which the stabilized diazo amino compound is produced may beany of the diazotizable aryl amines utilized in the azo dyestufi" art.Examples of such amines are given in the aforesaid Solomon patent and inmy aforesaid co-pending application Serial No. 562,033 and entitledElectrolytic Recording,

to which attention is directed. Such amines are, for example,naphthionic acid, 4.4'diamino-diphenyl-2.2-disulfonic acid,4.4-diaminodiphenyl 3.3'-disulfonic acid,4.4'-diaminodiphenylamine-Z-sulionic acid, orthotolidine-2.2-disulionicacid, alpha-naphthylamine-4.8-disulfonic acid,alpha-naphthylamine--sulfonic acid, 0- anisidinei-sulionic acid, and thelike. These amines when used in the form of the stabilized diazo aminocompounds may have their diazonium compounds stabilized with analiphatic amine such as ethanolamine, diethanolamine, carcosine,diisopropanolamine, diinethylamine, diethylamine, and the like, by anaromatic amine which does not readily couple, such as 4-sulfo-2-aminobenzoic acid, 2-methyl-amino-4-sulfobenzoic acid and the like, orby a heterocyclic amine, such as alpha-carboxy pyrrolidine,alp'ha-l-alpha-Z-dicarboxy pyrrolidine, piperidine, carbazole and thelike.

The stabilized diazo amino compounds are prepared by diazotizing theprimary aromatic amine and reacting the resulting diazonium compound inan alkaline solution with one of the aforesaid organic amines which doesnot easily couple to form an azo dye. It is advisable when producing thestabilized compound, to use an excess of the stabilizing amine over thequantity theoretically necessary to produce the stabilized diazoniumcompound since otherwise difficulties may be encountered in thestability of the records to light.

As the coupling component there may be used any naphthol sulfonic acidat least one sulfo group of which has been neutralized with analkylolamine. Such compounds have the following formula, assuming thatdiethanolamine is the neutralizing agent:

Z-naphthol-G-sulfonic acid 2-naphthol-8-sulfonic acid1-hydroxy-8-acetylamino naphthalene-3.6-diSu1- ionic acid 1hydroxy-S-amino naphthalene-3.5-disulfonic acid l-hydroxy 8 aminonaphthalene-6.7-disulfonic acid 1.8-dihydroxynaphthalene-3.6-disulfonicacid l-hydroxy 8 amino naphthalene-3.6-disulfonic acid l-hydroxynaphthalene-3.6-disulfonic acid 2-hydroxy-naphthalene-3.6-disulfonicacid 1.7-dihydroxy naphthalene-3.6-disulfonic acidZ-hydroxynaphthalene-G.8-disulfonic ac-id1-hydroxynaphthalene-3.6.8-trisulfonic acid1.3-dihydroxynaphthalene-5.7-disulfonic acid1.5-dihydroxy-naphthalene-2.7-disulfonic acid1.5-dihydroxynaphthalene-3.7 -disulfonic acid1.7-dihydroxynaphthalene-3.7-disulfonic acid l-hydroxy '7 aminonaphthalene-3.6-disu1fori ic acid and the like. Best results, however,have been secured with the salts of chromot'ropic acid and the use ofthe salt of this acid represents the preferred embodiment of myinvention.

The preparation of the alkylolamine derivative of the coupling compoundmay be carried out by dissolving the alkyl'olamine in a volatile, inertsolvent such as alcohol, and reacting the coupling component with thesolution of the alkylolamine. Upon heating to a temperature of to C.,the excess alkylolamine is removed with the alcohol. a solvent,morpholine may also be employed and by proportioning the quantities ofthe alkylolamine and the morpholine a mixed alkyola'minem'orpholine saltis obtained.

It has been previously pointed out that at least one of the sulfonicacid groups of the coupling component is neutralized with thealkylola'inine'. If the naphthol sulfonic acid employed is amonosulfonic acid, only the monoamine salt is formed, in which case thepreparation is effected by using 1 mol of the. naphthol sul'foni'c acidwith at least 1 mol of the alkylolamine. Where the coupling component isa polysulfonic acid, the ratio of the reactants will vary depending uponthe particular naphthol polysulfonicacid selected and the resultsdesired. If, for instance, a disulfonic acid such as ohromotropic acidisused-,

It might be noted'th'at as such amonoamine salt may be prepared by using1 1 mol of the-sulfonic acid for each molof the algroup is neutralizedwith an alkylolamine and" another group is neutralized by means ofanother radical. Thus, by using 'a" naphthalene disulfonic acid such aschromotropic acid, with l mol of an alkylolamine and 1 mol ofmorpholine', the mixed alkylolamine-morpholine salt results.

The dry mixture which is used, irrespective ofthe source of thediazonium compound,must con-- tain an electrolyte, The electrolyteispreferably sodium chloride, although other common electrolytes such aspotassium chloride, sodium bromide I and the like may be utilized withequally good results.

The preferred pH of the solution resulting from dissolving the drymixture in water is between 9.5 and 11.5. In some instances, thealkalinity afforded by the salt of the coupling agent will not give thepH which is optimum for the component used. In that case, it isdesirable to add a very small amount of an inorganic alkali such assodium hydroxide, potassium hydroxide or the like. The quantity of thisagent required will usually be from 1 to 2 grams per literof therecording solution.

Other ingredients may be incorporated-in the dry mix and in particular awetting agent to facilitate the impregnation of the carrier by thesolution. Suitable wetting agents are alkyl naphthalene sulfonic acids,for example, butyl naphthalene sulfonate and the like, the condensationproduct of a sulfonated benzene with chlorinated kerosene, said compoundhaving the formula SOaNB where R represents the hydrocarbon radicalspresent in kerosene (see U. S. P. 2,220,099), and sarcosine andtaurines, the nitrogen atom of which is acylated with a high molecularweight fatty acid, for example, oleic, palmitic and the like. Thewetting agent will usually be present in an amount ranging from .05 toabout 1 gram per liter of solution.

The invention will be further understood from the following examples,but it is to be remembered that these examples are illustrative and notlimitative.

Example I .06 gram mols of diethanolamine are dissolved in cc. of ethylalcohol.

.03 gram mols of dry, finely ground chromotropic acid is slurried fromone-half hour with this ethyl alcohol solution. The product is thendried at a temperature of 65 to 70 C. There is thus obtained apurple-gray product having a dry weight of 21.42 grams and which is thedi-salt of diethanolamine chromotropic acid.

.2 gram mol of diethanolamine salt of chromotropic acid, .4 gram mol ofthe diazo compound from diazotized naphthionic acid and diethanolamine,

3.3 grams of the condensation product of naphthale'ne sulfonic acid withchlorinated kerosene,

163.8grams of sodium chloride, and 8.2 grams of sodium hydroxide arethoroughly ground and mixed together to produce a uniform dry product.

74.5 grams of this mixture are dissolved in a liter of Water for thepreparation of a facsimile recording solution, This solution has a pH of10.1. Records produced with such a solution are a dark blue purple, thebackground of which has a high stability to light.

The diazo amino compound from diazotized naphthionic acid anddiethanolamine referred to andice. Diazotization is complete almost assoon as the solution is added and the diazonium com-= pound, which isquite insoluble, precipitates out as a thick, creamy slurry. Stirring iscontinued for one hour to obtain the product in a form in. which it ismore easily filtered. Filter cake ob tained upon filtration isreslurried in approxi-- mately 500 cc. of water until a smooth paste is:obtained. This paste is added slowly at 10 to 15 C. over a two-hourperiod with rapid agitation tor a solution of cc. of diethanolamine in250 cc. of water while maintaining a temperature of 10 to 15 C. in anice bath to minimize decomposition.

The reaction is complete when all the diazoniuin compound has beenadded. Th resulting solution is amber in color and may stain paper witha reddish tint. It must be alkaline when tested with brilliant yellowtest solution.

2 grams of sodium hydrosulfite are added and the solution stirred forone hour at room temperature to clear away the red-staining impurities.20 grams of activated charcoal are incorporated and the temperatureraised to 50 to 55 C. for /2 hour for the purpose of further clarifyingthe solution and to remove basic impurities. Sodium y chloride is thenadded to precipitate the diazomum compound which is filtered off, washedand dried.

Example II 30 cc.of ethyl alcohol.

.03 mol of chromotropic acid in a dry, finely ground condition isslurried for one-half hourwith this ethyl alcohol solution. The product.obtained upon drying at 65 to 70 C. has a dry Weight equal to 18.74grams and is the di-mono-- ethanolamine salt. It is a dark gray incolor.

This salt of monoethanolamine is employed in: the same manner as thediethanolamine treated; chromotropic acid of Example I to give a drymix: suitable for electrolytic recording solutions. Bluepurple recordsof a good background stability to-- light are obtained upon submitting areceiver treated with a water solution of the dry mix to the action ofan electrolytic current.

Example III .06 mol of triethanolamine are dissolved in 20 cc. of ethylalcohol.

.03 mol of chromotropic acid in a dry, finely" ground condition areslurried with the alcohol so lution forhalf anhour and thereactionproduct-i is then dried 8.1365 to 70 C. The product obtainedin-adryweightof 23.66 grams is a slightly gummy,

dark brown powder and is the di-triethanolamine salt.

The product when substituted for the diethanolamine treated chromotropicacid of Example I produces a dr mix which when used in electrolyticrecording gives a blue-purple record.

Example I V' The procedure is the same as in Example I except that thechromotropic acid is replaced by l-hydro'icy-S-aminonaphthalene-'6."I-disulfonic acid. I

Example VI The. procedure is the same as in Example I' except that thechromotropic acid is replaced by2 hydroxy-naphthalene-3.G-disulfonicacid.

Example VII The procedure is the same as in Example I exceptv that thechromotropic acid is replaced by 1.7-dihydroxy-naphthalene-3.fi-disulfonic acid.

Various modifications of the invention Will occur to persons skilled inthe art. and I therefore do notintend to be limited in the patentgranted except as required by the prior art and the appended'claims.

I claim:

1. A storage-stable, dry mix for producing electrolytic recordingsolutions containing as its essential components a diazo amine compoundcapable of yielding a diazonium compound under the influence of anelectrolytic recording current, a water soluble inorganic salt as theelectrolyte in an amount to insure passage of the electrolytic recordingcurrent and a sufficient quantity. of a preformed salt of a naphtholsulfonic acid to couple with the. diazonium compound whenformedltoproducean azo dyesaid'preformed salt.

having. the following constitution:

in which R is a member of the class consisting of. hydrogen, aminoandacylamino, m is a num;

her from 1 to 3, n is a number from 1 to 2, and

Y is. a quaternary ammonium radical selected.

from the class consisting of monoethanol-ammonium, diethanol-ammonium,triethanol-ammonium, and di-isopropanol-ammonium, said compositionw'hendissolved in water having a pH on the alkaline side any inorganic alkalipresent being inan amount not greater than 2 grams per liter ofrecording solution.

2.. A storage-stable dry mix for producing electrolytic recordingsolutions containing as its'essential components the diazo aminocompound of! diazotized naphthionic acid and diethanolamine capableofyielding: a diazonium compound undertheinfluence of an electrolyticrecording current,-.awater'soluble inorganic salt as the electrolyte in.an amount to insure passage of the.

electrolytic recording current, and a sufiicient quantity of apreformeddiethanolamine salt of v chnomotropic acidtocouple with the diazoniumcqmpound when formed to produce an azo dye,.

said composition when dissolved in Water having a pH on. thealkalinesideany inorganic alkali present being in an amount not greater than 2grams per liter ofrecording solution.

3 A fibrous sheet material impregnated with.

an aqueous solution of thecomposition of claim 1.

4. A fibrous. sheet. material impregnated. with an: aqueoussolution-of.the-composition of claim 2.

HAROLD G. GREIG.

REFERENCES. CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2 ,088,506 Chambers July 27, 19372135;964 Dahlen Nov. 8, 1938 2,138,572 Etzelmiller Nov. 29; 1938 233153370 Nodler A r; 6, 1943- 2,42'1' ,3'6 7 Solomon May 27, 1947'2,440.526 Solomon Apr. 27, 1948

1. A STROAGE-STABLE DRY MIX FOR PRODUCING ELECTROLYTIC RECORDING SOLUTIONS CONTAINING AS ITS ESSENTIAL COMPONENTS A DIAZO AMINO COMPOUND CAPABLE OF YIELDING A DIAZONIUM COMPOUND UNDER THE INFLUENCE OF AN ELECTROLYTIC RECORDING CURRENT, A WATER SOLUBLE INORGANIC SALT AS THE ELECTROLYTE IN AN AMOUNT TO INSURE PASSAGE OF THE ELECTGROLYTIC RECORDING CURRENT AND A SUFFICIENT QUANTITY OF A PREFORMED SALT OF A NAPHTHOL SULFONIC ACID TO COUPLE WITH THE DIAZONIUM COMPOUND WHEN FORMED TO PRODUCE AN AXO DYE SAID PREFORMED SALT HAVING THE FOLLOWING CONSTITUTION: 